Reversible gear pump

ABSTRACT

A sleeve-encased cartridge-type, unidirectional-flow, gear pump for compressors and the like having circumferentially aligned inlet openings in a stationary sleeve wall adjacent a covered end portion of the cavity thereof, and within said end portion an indexible flow connector block rotatably supported for turning to opposite limits of movement on a fixed concentric support. The block is resiliently urged against the end faces of an internal spur gear pump housed in the opposite end portion of the sleeve cavity, the inner gear of said pump being mounted on a pinion having a stationary axis offset from the sleeve axis and projecting from the end of said concentric block support, and the outer ring gear being rotatably supported by the sleeve wall. A drive connector plate engageable on the end of a compressor input shaft has a driving engagement to rotate the outer ring gear. The connector also has sealed passage means for joining an axial lubrication bore of an input shaft with a pump outlet bore in the offset pinion and the block support. One of a pair of radially directed passages in the support is connected to said outlet bore and the pump outlet side by an angled outlet passage of the indexible block at opposite limits of movement. An angled inlet passage in the block correspondingly connects the low pressure inlet side of the pump with an opening of the stationary sleeve wall.

United States Patent [191 Albrecht et al.

[ Mar. 12, 1974 [5 REVERSIBLE GEAR PUMP [75] Inventors: Clifford C. Albrecht, Leicester;

Howard G. Brown, Worcester, both of Mass.

[73] Assignee: Novelty Tool Company, Inc.,

3 Spencer, Mass.

[22] Filed: Dec. 13, 1972 211 Appl. No.: 314,855

52 us. c1. 418/32, 417/315 Primary Examiner-Carlton R. Croyle Assistant ExaminerRichard Sher Attorney, Agent, or Firm-Chapin, Neal and Dempsey [57] ABSTRACT A sleeve-encased cartridge-type, unidirectional-flow,

gear pump for compressors and the like having circumferentially aligned inlet openings in a stationary sleeve wall adjacent a covered end portion of the cavity thereof, and within said end portion an indexible flow connector bloclcrotatably supported for turning to opposite limits of movement on a fixed concentric support. The block is resiliently urged against the end faces of an internal spur gear pump housed in the opposite end portion of the sleeve cavity, the inner gear of said pump being mounted on a pinion having a stationary axis offset from the sleeve axis and projecting from the end of said concentric block support, and the outer ring gear being rotatably supported by the sleeve wall. A drive connector plate engageable on the end of a compressor input shaft has a driving engagement to rotate the outer ring gear. The connector also has sealed passage means for joining an axial lubrication bore of an input shaft with a pump outlet bore in the offset pinion and the block support. One of a pair of radially directed passages in the support is connected to said outlet bore and the pump outlet side by an angled outlet passage of the indexible block at opposite limits of movement. An angled inlet passage in the block correspondingly connects the low pressure inlet side of the pump with an opening of the stationary sleeve wall;

9 Claims, 3 Drawing Figures REVERSIBLE GEAR PUMP BACKGROUND OF THE INVENTION This invention relates to gear pump devices of a car- 5 tridge assembled construction producing a unidirectional outlet flow regardless of the direction of gear rotation. Small gear pumps of this nature are commonly used in compressor units for bearing lubrication purposes and are conventionally known as automatically 1 reversible pumps. Such units operate to provide a common outlet passage for high pressure fluid whether the input to the pump rotates in a right or left hand direction and thus serves to eliminate any difficulties requiring the matching of input shaft rotation to a correct 1 gear pump rotation.

In the prior art such devices are of various and sundry constructions. The cartridge type of assembly is widely used at the present time because easier to handle as a sub-assembly for incorporating into a compressor unit and desirably requires merely the connection with a pump input drive shaft and then an anchoring in operative position on the compressor housing or framework. Two examples of such devices, and the nearest prior art known, are disclosed by 1967 U.S. Pat. No. 3,343,494

for the pump itself. An object of the present invention is to provide a specifically different pump structure for accmplishing the same general end result and one which may more readily be adapted for incorporation in a variety of different compressor designs. More particularly, the units of the above patents are characterized by a sleeve structure in which an input shaft connection is made with the end of the sleeve encircling the end of the input shaft for the purpose of driving the pump by rotating the sleeve as in the first mentioned patent or for alignment purposes as disclosed in the second reference. In the device of the present invention a sleeve-encased pump and directional flow control means is provided in which the driving connector means for attachment to the input shaft is exteriorly disposed relative to the end of a sleeve and permits, as will be hereinafter described, a wider lattitude in adapting a basic pump cartridge of a given size or capacity for many different compressor designs merely by modifying the driving connector.

.Another object is to provide a device in which the inlets for the pump are formed in the wall of the sleeve itself by a series of circumferentially aligned openings thus again rendering the unit more readily adaptable for use in specifically different compressor assemblies without major alterations. In other words, such inlet openings are conveniently available for connecting to an inlet reservoir or supply line whatever the specific compressor structure, and thus a basic cartridge unit may be employed for a wide range of compressor designs without extensive alteration of either the cartridge or basic compressor structure. A companion ad vantage of the circumferentially arranged sleeve wall inlet openings and specific arrangement of indexible pump inlet and outlet connector passages lies in the rel- 65 ative ease with which the parts may be assembled and the cartridge installed since the chance for any misalignment is minimal.

SUMMARY OF THE INVENTION The invention in its preferred f-orm contemplates a shell-like cylinder or sleeve having a cover plate or cartridge mounting member closing off one end thereof. From this end member a cylindrical support extends concentrically inside the adjacent inner portion of the sleeve and carries at its outer end a gear pinion on an axis offset from the sleeve axis. The pinion is hollow and connects with a pair of diametrically opposed radial passages in the cylindrical support.

Rotatably mounted on the support is a flow control block with means interconnecting the stationary plate and movable block to provide an indexing limit of 5 travel of The block is spring-pressed away from the plate against the end faces of'inner and outer internal spur gear pump elements. The inner gear is mounted on the hollow pinion and the ring gear is rotatably supported in the sleeve wall. The ring gear carries drive pins projecting outwardly of the end of the sleeve and loosely engaged at their outer headed ends in openings of a drive connector or adapter plate which is engaged on the end of a compressor input shaft preferably by a slidable pin and key-way slot drive connection. The plate also has a central opening with an O- ring for pressing against the end face of an input shaft and the sealed connection of the passage from the hollow bore of the pinion to a lubrication inlet line on the 7 axis of the input shaft.

The inlet to the pump gears is formed by circumferentially aligned openings in the shell wall opposed to the periphery of the indexible control block and registrable at each limit of 180 travel with the single angled inlet connector passage of the block. This latter connector passage is indexible to communicate at each limit of block movement with the inlet side of the gears. Diametrically opposed to the inlet is an angled outlet passage likewise registrable-with the outlet side of the gears and with one of said radial passages in the block support.

The end cover plate and sleeve are preferably flanged and provided with matching bolt holes for anchoring the pump cartridge in place for operation as the drive connector plate is moved into engagement on the input shaft.

FIGURES FIG. I is a longitudinal sectional view ofa cartridgeassembled gear pump unit embodying the invention and mounted on the end of a compressor input shaft;

FIG. 2 is a view similar to FIG. I on a smaller scale showing substantially the same unit as modified for installation on a compressor of a different design; and

FIG. 3 is a sectional view on line 3-3 of FIG. 1

DESCRIPTION OF THE INVENTION A cartridge-type pump assembly embodying the present invention is shown by FIG. I mounted for operation on the end of an input drive shaft as the crank shaft 2 of a compressor unit. An axial bore 4 in the shaft for bearing lubrication is connected to the outlet side of the pump as will be later described. The end face of shaft 2 is indicated as recessed within a cylindrical well of a compressor housing schematically outlined by dotdash lines at 6. An annular spacing between the outer wall of the pump casing and encircling wall of the well thus provides a reservoir for inlet oil to the pump. The reservoir at the inlet side of the pump cartridge unit may be otherwise formed and the pump readily adapted for compressors of various specifically different constructions, the well 16 and recessed shaft 2 of FIG. 1 being illustrative of a typical installation.

The pump cartridge is formed with a cylindrical sleeve 8 and an end cover mounting plate 10 over the end of the sleeve to provide a stationary pump housing structure. As in FIG. 1 sleeve 8 and cover plate It) are preferably formed with mating annular flanges in which a series of registered openings, as the bolt hole at 12, are provided for the stationary mounting thereof in fixed anchored relation against the outside compressor wall 6. A cylindrical body portion at 14 of the cover plate 10 is received in the flanged end of the sleeve cavity preferably with a loose friction fit for each in assembly and take-down purposes, and a gasket at 16 seals the mating surfaces of the flanges.

At the opposite open end of the sleeve and in the outer portion thereof is a rotatably supported ring gear 18 of an internal spur-gearpump, the inner gear being at 20 and mounted as will be described. Press fit in longitudinal openings of gear 18 are drive pins, one of which is at 22 and shown as having a projecting headed end 24 received in a stepped opening 25 of a cupped drive connector plate 26 engaged on the end of shaft 2. Plate 26 has a shallow cylindrical flange 27 slidably fitting over the end of shaft 2 with a radially inwardly directed drive pin 28 engaging a key-way-type of slot 30 at the edge of the shaft. As shown plate 26 also has a central opening 32 communicating with bore 4 of the shaft. Surrounding this opening is an O-ring seal 34 carried on the plate for pressing against the end face of shaft 2 around the flared entrance to bore 4 and sealing the passage.

Within the closed end of the sleeve, the end cover plate is provided with an integrally projecting cylindrical support 36 concentrically disposed relative to sleeve 8 and-forming a member on which an indexible flow connector or control block 38 is rotatably supported for limited arcuate movement as will be described. From the outer end of the support 36 an inner gear pinion 40 projects on an axis offset from the axis of the concentric sleeve and support. Mounted for rotation on pinion 40 is the inner gear 20 in meshing engagement with ring gear 18.

Pinion 40 is hollow and anchored in a longitudinally recessed passage 42 at the end of support member 36. In communication with this longitudinal passage 42 through the wall .of the pinion are diametrically opposed radial passages 44 and 46. Passages 44 and 46, the bore of pinion 40 and opening 32 of plate 26 together form a stationary cartridge outlet passageway for pump discharge to the input shaft bore 4.

The indexible block 38 is spring pressed outwardly on the support member 36 by a compression spring 48 seated in surrounding relation to the support against plate 14 and against a shoulder provided bh arcuately recessed portions 50 and 52 of block 38. The recess at 51 cut in the edge of block 38 has an arcuate length of about 180 and the recess 50 is cut to receive the spring. Projecting into recess 52 from cover plate 14 is a stop pin 54 for limiting rotatable indexing of the block to a 180 movement (see also FIG. 3).

Block 38 lies in covering relation to a series of openings in the wall of sleeve 8. A pair of diametrically opposite openings are shown at 56 in FIG. 1. The series of openings 56 lie in spaced circumferentially aligned relation (see FIG. 3) preferably all around the sleeve and provide inlet passages for connecting the reservoir with the inlet side of the pump gears.

In block 38 an inlet connector passage is at 58 and an outlet connector passage at 60, both connectors being angularly directed as shown. Diametrically opposed longitudinal portions are open to the end faces and between the inner and outer pump gears to connect the inlet and outlet sides of the pump regardless of the direction of gear rotation. Inlet 58 is provided with a radially outwardly directed portion to register with inlet openings 56 of the sleeve wall. Outlet passage 60 is radially inwardly directed to register with radial passage 46 or 44 at the opposite limits of indexing movement of control clock 38.

It will be seen that when drivingly connected to shaff 2, spring 48 presses block 38 against the end faces of pump gears 18 and 20, the latter also engaging plate 26 with a running fit and urging the plate in the direction of shaft 2. The gears being in frictional engagement with block 38 will urge the latter in either direction of rotation to engage one end of the arcuate recess 52 against the stop pin 54. In FIG. 1 the gears, rotating in a clockwise direction as viewed from the left of FIG. 1, will maintain the upper end wall of recess 52 as shown against pin 54. As so indexed, outlet 60 lies in registration with the radial passage'46 and the outlet side of the pump. Inlet 58 is registered with the inlet side of the gears and with inlet port 56 at the lower side of the sleeve wall. In the event the gears are reversely driven as in a counterclockwise direction, the block will be frictionally rotated and indexed through an arc of 180 to engage the opposite end of recess 52 against pin 54 and thus oppositely index the angled inlet and outlet conduits. The outlet 60 will then be connected to radial passage 44 and the inlet 58 connected to the opposite upper wall opening 56. A longitudinal passage at 57 in the edge of block 38 connects inlet 58 with the back side of the block.

The inner gear 20 being on the stationary axis of pinion 40 both inner and outer gear cooperate to turn block 38 in the direction of rotation. For a freely balanced running action of inner gear 20 on pinion 40 it may also be noted that the outer end face of gear 20 is provided with a recessed portion at 62 between the outlet end of the hollow pinion 40 and the opening 32 of plate 26. This enables the high pressure outlet flow to provide a degree of back pressure against the end of gear 20 and to some extent float the gear for smoother running between the plate and end of support 38. It will be clear that the pressure of spring 48 may normally carry the gear slightly beyond the end face of the support. It may also be appreciated that if in any given installation a greater spring pressure is desirable a suitable disk washer (not shown) may be inserted for the spring seat.

With the combination and relationship of parts as shown in FIG. I it will be apparent that the basic components of the assembly can be utilized without dimensional charges in the gears etc. in order to accommodate compressor units having a variety of specifically different mounting means for installing the pump. For example, an input shaft as the shaft 2 may be of a larger or smaller diameter and since the sleeve 8 of the cartridge unit does not engage the input shaft, the connector plate element only need be modified for suitable operation. For smaller diameter shafts an adapter ring (not shown) having a shaft drive pin may be secured within the flange. For larger diametershafts a plate 26 of suitably larger diameter can be substituted and the drive pin openings appropriately located to receive the headed ends of the ring gear pins. As for the mounting flanges at the other end of the cartridge unit, these may obviously be also modified without dimensionally altering or otherwise changing the other parts of the assembly. Accordingly, the present construction permits more economical production of cartridge assemblies adaptable for use on a wider range of compressor units having specifically different mounting requirements.

In FIG. 2 an assembly is shown in which a pump cartridge unit having substantially identical operational characteristics and which may have the same sleeve diameter with identical internal parts is mounted for operation on the reduced end of an input shaft 2'. The end face of the shaft lies approximately in the plane of the compressor housing wall support indicated at 6. In this unit the discharge passage is double-ended leading not only to an inlet shaft bore at 4' but also back through the cover plate 10' and across by passage 70 to the flanged portions and to a discharge line 72 in the wall of a pump casing adapter 73. Adapter 73 is representative of a specifically different mounting element as used for fitting the reversible gear pump into another design of 'a compressor model.

As will be understood in the compressor art, the discharge line 72 of the adapter is for lubricating unloaders. An inlet line 74 is located in the opposite adapter wall for supplying the pump reservoir. A mounting flange 76 is for anchoring to the wall support at 6'.

The pump unit is mounted by anchor bolts in holes (one of which is shown at 12) of the mating flanges of end cover 10' and sleeve 8' and seating the same at the outer end of adapter 73. As shown, a spherical roller bearing 80 encircles shaft 2' rearwardly of the reduced end thereof and this bearing together with the inner wall of the adapter cavity forms a well to receive the pump sleeve and shaft drive connection for operation surrounded by an annular inlet reservoir, all as .described in connection with FIG. 1.

The'adapter inlet line at 74 receives oil from a branch passage 82 which is connected to the source line (not shown and at the end of the adapter casing 73 the facing surface of the sleeve flange is relieved as at 84 for communication with the annular reservoir. The outer wall of the sleeve is also annularly recessed in the area of the inlet openings therein for improved clearance relative to the restriction at the mouth of the well. Accordingly, with the major exception of the additional outlet passage 70 through the end plate the basic construction of the cartridge and parts thereof is identical .with the assembly shown by FIG. 1.

From the above it will be noted that the mounting of a pump unit for operation is readily accomplished by simplly sliding it into the well cavity of the compressor or adapter, and indexing the drive pin 28 to engage the key-way slot of the input shaft. Once this latter connection is made the mating flanges of the sleeve and end plate can be seated by the suitable attachment of an- Other normal problems of alignment usually encountered in this type of installation are: automatically compensated for. For example, the loose fit of the headed ends of the ring gear drive pins in stepped openings of the connector plate on the drive shaft permits satisfactory'driving engagement in the manner of a universal joint and requires no precise accuracy in alignment of the cartridge mounting holes of the housing with re spect to an input shaft axis. The O-ring seal between the connector plate and end face of the input shaft insures a sealed discharge from the: pump to the shaft bore without requiring a shaft end face to be accurately squared with respect to the shaft axis and plane of the cartridge mounting surface.

In the cartridge unit itself the indexing stop pin of the cover plate is initially aligned diametrically with the offset axis of the inner gear pinion and the axis of the radial outlets of the support for the: indexible block are likewise aligned therewith. With this arrangement there is no opportunity to assemble parts incorrectly nor any need for accurate alignment in mounting on the compressor except, as mentioned above, for the drive pin and shaft engagement. Thus skilled workmen are not needed for unit assembly work nor for the later installation on a compressor.

Also from the manufacturing standpoint, an outlined previously, the present structure is readily adapted for the use of an outer stationary shell member having a diameter of a given size and enclosing therein identically dimensioned pump parts so that the drive connector plate or mounting flanges only need be modified to fit various compressor models of different makes and largely eliminate the need for more or less completely individualizing pump designs for each compressor model. This results in obvious savings in production costs as well as costs for parts design modifications.

What is claimed is:

1. In a unidirectional-flow gear pump assembly of the cartridge-type having a housing with a stationary sleeve having inner and outer end portions, and a cartridge mounting cover plate closing off the inner end of the sleeve; a gear pump having an inner gear and an outer ring gear rotatably supported in the outer end portion of the sleeve with means for drivingly connecting said ring gear to an input shaft; and flow control means including an indexible annular block in the inner end portion of the sleeve automatically providing a unidirectional flow from said pump regardless of the direction of rotation of the gearpump elements;

said sleeve having a wall portion spaced inwardly of said pump gears provided with a series of circumferentially aligned inlet wall openings,

a stationary cylindrical supporttextending from said plate concentrically within the inner sleeve portion and a pinion projecting therefrom on a fixed axis offset from the axis of the sleeve and rotatably supporting the inner gear of said pump.

said cylindrical support having a longitudinal outlet bore in communication with the exterior of said housing assembly, and a pair of radial passages connected to said bore with entrance openings in spaced circumferentially aligned relation on the support surface, and

said annular block rotatable on said support between opposite limits of arcuate travel, indexing movement of said block toward and away from each limit of travel being responsive to the direction of rotation of said gear pump due to friction, said block having an angled inlet conduit with a radial section communicating with one of said sleeve inlet openings at each limit of travel and a longitudinal section connecting the inlet side of said gear pump regardless of the direction of gear rotation, and an angled outlet conduit with a longitudinal section connecting the outlet side of said gear pump at each limit of travel and a radial section communicating with a radial passage of said support regardless of the direction of gear rotation.

2. A cartridge-type unidirectional flow gear pump assembly including an end cover plate, a stationary cylindrical sleeve extending therefrom having circumferentially aligned inlet openings in the sleeve wall spaced inwardly of an open end portion thereof, an outer ring gear supported for rotation in said open end portion and having drive means for connection with an input shaft, V

a stationary cylindrical support member extending concentrically within the sleeve from said cover plate having a pair of spaced circumferentially aligned radial outlet passages and a longitudinal passage connecting the inner ends thereof and in communication with the exterior of said assembly,

an annular connector block rotatably supported on said support member between said radial outlet passages and said sleeve inlet openings, means to limit arcuate movement of said block, and a pinion extending from the end of said support having an inner pump gear rotatably mounted thereon in meshing engagement with said ring gear, the stationary axis of said pinion being offset from the axis of said concentric member and sleeve,

said block being yieldably urged endwise in the direction of said gears and being frictionally indexible thereby to one of said limits of arcuate movement, said block having angled inlet and outlet conduits, the inlet conduit having a radial end portion communicating with one of said sleeve wall openings and an axially directed end portion communicating with the inlet side of the pump gears at each limit of block movement, the outlet conduit having an axially directed end portion communicating with the outlet side of said gears at each limit of block movement, and a radial end portion communicating with one of said radial passages of the support member.

3. The structure of claim 2, in which,

the radial passages in said support are diametrically aligned, the inlet and outlet conduits of said block are positioned in diametrically opposed relation and the limited indexing movement of said block is through an arc of 4. The structure of claim 3, in which,

said input shaft drive connector means includes,

a drive pin fixed in said outer ring gear, and

a driving plate having a loose fit connection with the outer end of said pin for limited radial and longitudinal shifting movement therebetween,

said plate having a key element for a longitudinally slidable key-way drive connection to an input shaft.

5. The structure of claim 4, in which,

said inner gear pinion is hollow and the bore thereof is in communication with said longitudinal passage of the support member,

said driving plate has a central opening in communication with the bore of said pinion, and means are provided on the plate for a sealed engagement against the end face of an input shaft around said plate opening. v

6. The structure of claim 5, in which,

the means for urging said block in the direction of said gears is a compression spring surrounding said support member and seated between said end cover plate and said indexible block.

7. The structure of claim 6, in which,

the outer edge of the indexible block facing said cover plate is formed with an arcuate recess of 180 and a pin fixed in said cover plate projects into the recess to provide the means for limiting arcuate movement of said block, and

said end face of the block is further annularly recessed adjacent said cylindrical support and said spring is seated therein and against said cover plate.

8. The structure of claim 7, in which,

said support member is an integral part of said end cover plate and said sleeve is formed separately therefrom, said plate and sleeve each having mating annular outwardly flanged portions provided with registrable bolt mounting holes.

9. The structure of claim 8, in which,

an outlet passage in said support member and flanged portions of the end plate and the sleeve is formed to provide an additional outlet passage leading to the exterior of said flanged portions. 

1. In a unidirectional-flow gear pump assembly of the cartridgetype having a housing with a stationary sleeve having inner and outer end portions, and a cartridge mounting cover plate closing off the inner end of the sleeve; a gear pump having an inner gear and an outer ring gear rotatably supported in the outer end portion of the sleeve with means for drivingly connecting said ring gear to an input shaft; and flow control means including an indexible annular block in the inner end portion of the sleeve automatically providing a unidirectional flow from said pump regardless of the direction of rotation of the gear pump elements; said sleeve having a wall portion spaced inwardly of said pump gears provided with a series of circumferentially aligned inlet wall openings, a stationary cylindrical support extending from said plate concentrically within the inner sleeve portion and a pinion projecting therefrom on a fixed axis offset from the axis of the sleeve and rotatably supporting the inner gear of said pump. said cylindrical support having a longitudinal outlet bore in communication with the exterior of said housing assembly, and a pair of radial passages connected to said bore with entrance openings in spaced circumferentially aligned relation on the support surface, and said annular block rotatable on said support between opposite limits of arcuate travel, indexing movement of said block toward and away from each limit of travel being responsive to the direction of rotation of said gear pump due to friction, said block having an angled inlet conduit with a radial section communicating with one of said sleeve inlet openings at each limit of travel and a longitudinal section connecting the inlet side of said gear pump regardless of the direction of gear rotation, and an angled outlet conduit with a longitudinal section connecting the outlet side of said gear pump at each limit of travel and a radial section communicating with a radial passage of said support regardless of the direction of gear rotation.
 2. A cartridge-type unidirectional flow gear pump assembly including an end cover plate, a stationary cylindrical sleeve extending therefrom having circumferentially aligned inlet openings in the sleeve wall spaced inwardly of an open end portion thereof, an outer ring gear supported for rotation in said open end portion and having drive means for connection with an input shaft, a stationary cylindrical support member extending concentrically within the sleeve from said cover plate having a pair of spaced circumferentially aligned radial outlet passages and a longitudinal passage connecting the inner ends thereof and in communication with the exterior of said assembly, an annular connector block rotatably supported on said support member between saiD radial outlet passages and said sleeve inlet openings, means to limit arcuate movement of said block, and a pinion extending from the end of said support having an inner pump gear rotatably mounted thereon in meshing engagement with said ring gear, the stationary axis of said pinion being offset from the axis of said concentric member and sleeve, said block being yieldably urged endwise in the direction of said gears and being frictionally indexible thereby to one of said limits of arcuate movement, said block having angled inlet and outlet conduits, the inlet conduit having a radial end portion communicating with one of said sleeve wall openings and an axially directed end portion communicating with the inlet side of the pump gears at each limit of block movement, the outlet conduit having an axially directed end portion communicating with the outlet side of said gears at each limit of block movement, and a radial end portion communicating with one of said radial passages of the support member.
 3. The structure of claim 2, in which, the radial passages in said support are diametrically aligned, the inlet and outlet conduits of said block are positioned in diametrically opposed relation and the limited indexing movement of said block is through an arc of 180*.
 4. The structure of claim 3, in which, said input shaft drive connector means includes, a drive pin fixed in said outer ring gear, and a driving plate having a loose fit connection with the outer end of said pin for limited radial and longitudinal shifting movement therebetween, said plate having a key element for a longitudinally slidable key-way drive connection to an input shaft.
 5. The structure of claim 4, in which, said inner gear pinion is hollow and the bore thereof is in communication with said longitudinal passage of the support member, said driving plate has a central opening in communication with the bore of said pinion, and means are provided on the plate for a sealed engagement against the end face of an input shaft around said plate opening.
 6. The structure of claim 5, in which, the means for urging said block in the direction of said gears is a compression spring surrounding said support member and seated between said end cover plate and said indexible block.
 7. The structure of claim 6, in which, the outer edge of the indexible block facing said cover plate is formed with an arcuate recess of 180* and a pin fixed in said cover plate projects into the recess to provide the means for limiting arcuate movement of said block, and said end face of the block is further annularly recessed adjacent said cylindrical support and said spring is seated therein and against said cover plate.
 8. The structure of claim 7, in which, said support member is an integral part of said end cover plate and said sleeve is formed separately therefrom, said plate and sleeve each having mating annular outwardly flanged portions provided with registrable bolt mounting holes.
 9. The structure of claim 8, in which, an outlet passage in said support member and flanged portions of the end plate and the sleeve is formed to provide an additional outlet passage leading to the exterior of said flanged portions. 